References of "Destain, Marie-France"
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See detailImprovement Of Spray Deposit Homogeneity Using A Pwm Spray Controller To Compensate Horizontal Boom Speed Variations
Lebeau, Frédéric ULg; El Bahir, L.; Destain, Marie-France ULg et al

in Computers and Electronics In Agriculture (2004), 43(2),

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension ... [more ▼]

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods have performance and price limitations. This paper describes a spray controller aiming to compensate the effect of the horizontal boom movements on the spray deposits homogeneity. The controller is based on three main components: a control law describing the relationship between nozzle speed, nozzle flow and spray deposit; a real time measurement of the boom horizontal speed variations using micro-machined capacitive accelerometers, and pulse width modulation (PWM) nozzle flow actuators. To assess the feasibility of such a controller, a single nozzle prototype was developed and tested in the laboratory, using a nigrosine solution. Spray coverage was measured using image analysis for field representative nozzle speed variations. The spray coverage uniformity using the controller showed about 51% compensation of the variations observed without it. [less ▲]

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See detailA Real-Time Grading Method Of Apples Based On Features Extracted From Defects
Leemans, Vincent ULg; Destain, Marie-France ULg

in Journal of Food Engineering (2004), 61(1),

This paper presents a hierarchical grading method applied to Jonagold apples. Several images covering the whole surface of the fruits were acquired thanks to a prototype grading machine. These images were ... [more ▼]

This paper presents a hierarchical grading method applied to Jonagold apples. Several images covering the whole surface of the fruits were acquired thanks to a prototype grading machine. These images were then segmented and the features of the defects were extracted. During a learning procedure, the objects were classified into clusters by k-mean clustering. The classification probabilities of the objects were summarised and on this basis the fruits were graded using quadratic discriminant analysis. The fruits were correctly graded with a rate of 73 %. The errors were found having origins in the segmentation of the defects or for a particular wound, in a confusion with the calyx end. [less ▲]

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See detailAnalysis of soil variability measured with a soil strength sensor
Hanquet, Bernard; Sirjacobs, Damien ULg; Destain, Marie-France ULg et al

in Precision Agriculture (2004), 5(3), 227-246

In the context of precision agriculture, the knowledge of soil strength variability at the field scale may be useful for improving site-specific tillage. Moreover, rapid and accurate sensing methods for ... [more ▼]

In the context of precision agriculture, the knowledge of soil strength variability at the field scale may be useful for improving site-specific tillage. Moreover, rapid and accurate sensing methods for soil physical properties determination would favourably replace labour intensive, time-consuming and expensive soil sampling and analysis. This study aims at validating conclusions of a previous study which was conducted to develop a soil strength in field conditions. The coupled acquisition of the sensor's signals and the corresponding DGPS positions allowed establishment of maps for the three measured outputs, namely the horizontal force (Fx), the vertical force (FZ) and the moment (My). In order to study the relationships between measured forces and soil physical parameters, a series of soil properties were measured on soil cores collected in 10 reference plots. Significant correlations were found between Fx and the average resistance to cone penetration at 25 cm depth and between Fx and the average soil moisture at 30 cm depth. The sensing method proved its capability to characterize within-field soil variability. [less ▲]

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See detailAnalysis of soil and crop properties for precision agriculture for winter wheat
Vrindts, Els; Reyniers, Marieke; Darius, Paul et al

in Biosystems Engineering (2003), 85(2), 141-152

In a precision farming research project financed by the Belgian Ministry of Small Trade and Agriculture, the methods of precision agriculture are tested on grain fields with a view of implementation of ... [more ▼]

In a precision farming research project financed by the Belgian Ministry of Small Trade and Agriculture, the methods of precision agriculture are tested on grain fields with a view of implementation of precision agriculture methods in Belgian field agriculture. The project encompasses methods for automatic information gathering on soil and crop and analysis of this data for management of within-field variability. Automatic information capturing is combined with traditional data sources of soil sample analysis and crop observations. The measurements and part of the results on one particular field in Sauvenière are presented here. Five nitrogen management strategies were compared, but the resulting differences in nitrogen dose were small and did not lead to significantly different yield results. The yield results were correlated to topography-related variations in soil texture and chemical components and to crop reflectance measurements in May. [less ▲]

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See detailSelection of the most efficient wavelength bands for 'Jonagold' apple sorting
Kleynen, O.; Leemans, Vincent ULg; Destain, Marie-France ULg

in Postharvest Biology & Technology (2003), 30(3), 221-232

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system ... [more ▼]

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system. Reflectance spectra of damaged and sound tissue were recorded using a visible/NIR spectrometer. Analysed defects consisted of scald, hail damage (with and without skin perforation), limb rubs, russets, scab tissue, frost damage, rot, visible flesh damage and recent bruises. Camera filter effects were approximated by summing the reflectances of all the wavelengths within the filter bandwidth. Combinations of three and four filters were tested and evaluated for discriminating damaged tissues from healthy ones. If a three-filter combination appeared sufficient to detect most of the damaged tissue, a four-filter combination should be considered for the complete sorting automation of this bicolour apple variety. A fourth filter was necessary to quantify the ratio between the blush and ground colours. Regarding recent bruise defects which represented the major difficulty, an image segmentation algorithm based on local contrast variations can enhance their detection. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailExternal quality grading of Jonagold apples using a multi-spectral vision system
Kleynen, Olivier; Leemans, Vincent ULg; Destain, Marie-France ULg

in Balsa-Canto E., Mora J.; Onate E. (Eds.) II International Workshop - Information Technologies and Computing Techniques for the Agro-Food Sector (2003)

This paper presents a method to sort Jonagold apples using a four bands multi-spectral image acquisition device. Multi-spectral images of sound tissue and various defects were acquired. Defects could be ... [more ▼]

This paper presents a method to sort Jonagold apples using a four bands multi-spectral image acquisition device. Multi-spectral images of sound tissue and various defects were acquired. Defects could be divided into four classes: slight defects (e.g. small russet), more serious defects (scar tissue), defects leading to the rejection of the fruit (e.g. rot) and recent bruises (between one hour and two hours old). Image segmentation was based on the Bayes' theorem. Each pixel of the fruit was classified into 'healthy' or 'defect' classes according to the probability distribution of the spectral components of each class. Once segmented, the fruit was graded by linear discriminant analysis on the basis of the relative area of the defect and statistical parameters computed on the spectral components of the two tissues classes. Results (cross validation) showed 94% and 84% if the sound and defective fruits respectively well classified. Most of the misclassified defective fruits (89%) belonged to the slight defect category. [less ▲]

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See detailEvolution of pressure distribution during apple compression tests measured with tactile sensors
Kleynen, Olivier; de la Cierva, Sonia; Destain, Marie-France ULg

in Acta Horticulturae (2003), (604),

The paper analyses the ability of thin-film tactile sensors in providing information during static compression tests of ‘Jonagold’ apples (Malus pumila) of different ripeness stages. Such sensors are able ... [more ▼]

The paper analyses the ability of thin-film tactile sensors in providing information during static compression tests of ‘Jonagold’ apples (Malus pumila) of different ripeness stages. Such sensors are able to measure the contact surface and the interfacial pressure distribution during compression of fruits, this latter being characterised by suitable mathematical parameters. Results of compression tests between two flat steel plates are presented. The differentiated evolution of the pressure distribution according to the fruit maturity is pointed out. Ability of the sensor in evaluating the firmness is also discussed. [less ▲]

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See detailContrôle des produits agroalimentaires par analyse d'images
Leemans, Vincent ULg; Kleynen, Olivier; Destain, Marie-France ULg

in Nouveaux capteurs pour la maîtrise de la qualité des produits agroalimentaires - Etat de la recherche européenne (2002, November 22)

Présentation de méthodes utilisées dans un processus de contrôle de qualité basé sur l'analyse d'image, en se focalisant sur la couleur et la forme des produits et leur classification

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See detailOn-line soil mechanical resistance mapping and correlation with soil physical properties for precision agriculture
Sirjacobs, Damien ULg; Hanquet, Bernard; Lebeau, Frédéric ULg et al

in Soil & Tillage Research (2002), 64

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their ... [more ▼]

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their influence on plant development and yields. The aim of this research was to develop and test in field conditions a sensor measuring on-line soil strength variations. The sensor was constituted of a thin blade pulled in the soil at constant depth and speed and a beam which transferred the soil–blade forces to a transducer fixed on the machine. This transducer measured the draft force (Fx), the vertical force (Fz) and the moment (My). A field experiment was performed in 2 ha field of silt soil (Hesbaye, Belgium). A soil strength map of the field was established by pulling the sensor at 5 m interline separation by a tractor equipped with a DGPS receiver. The relationship between the recorded forces and several soil physical parameters was studied by identifying 10 control plots on the sensor track. In each of them, cone index penetrometry profiles and soil water content were measured. Soil samples were taken in the centre of the plots to determine cohesion and internal friction angle, simple compression resistance, Atterberg limits, granulometry and pF curves. Triaxial tests identified over-consolidated soils in plots situated in the pounds of the field. Based on the parameters measured in the other plots, significant relationships were established between (1) a global penetrometry index and the Fx and My solicitations measured by the sensor; (2) gravimetric water content and the vertical force Fz. Interpolation by inverse distance with a range of 45 m gave the best result for the cartography of the three measured signals (Fx, Fz and My). The confrontation of those maps with pedological and topographic maps together with the statistical relationships and the farmer’s knowledge of the field showed high consistency. The results of this experiment in field conditions are encouraging and show the promising perspective of technological innovations allowing on-line characterisation of soil physical state for precision agriculture. [less ▲]

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See detailMeasurements Of The Horizontal Sprayer Boom Movements By Sensor Data Fusion
Ooms, David ULg; Lebeau, Frédéric ULg; Ruter, R. et al

in Computers and Electronics In Agriculture (2002), 33(2),

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See detailOn-line fruit grading according to their external quality using machine vision
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in Biosystems Engineering (2002), 83(4), 397-404

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits ... [more ▼]

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits (528 Golden Delicious, 642 Jonagold) belonging to the three acceptable categories-Extra, I and II-and the reject (each class represents, respectively, about 60, 10 and 20% of the sample size). The image grading was achieved in six steps: image acquisition; ground colour classification; defect segmentation; calyx and stem recognition; defects characterisation and finally the fruit classification into quality classes. The proposed method for apple external quality grading showed correct classification rates of 78 and 72%, for Golden Delicious and Jonagold apples, respectively. Taking into account that the healthy fruit were far better graded and considering that this class was under represented in the sample compared with the fruit population, the results of the proposed method (an error rate which drops to 5 and 10%, respectively) are compatible with the requirements of European standards. (C) 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailSpray pattern simulation model for standardisation of boom behaviour tests.
Lebeau, Frédéric ULg; Bouchat, X.; Ruter, R. et al

in Aspects of Applied Biology (2002), (66),

Simulation models of spray pattern are required for the dynamic behaviour assessment of sprayer booms. The reasons are their ease of use and their independence regarding variable operating conditions such ... [more ▼]

Simulation models of spray pattern are required for the dynamic behaviour assessment of sprayer booms. The reasons are their ease of use and their independence regarding variable operating conditions such as liquid properties and nozzle state, which interfere with the discrimination between various dynamic behaviours properties. Although such models have been developed for many decades, no international consensus has been reached on their use in a standardised test procedure. A consensual model is tested in the scope of standardisation specific needs. It uses ISO-5682/1 spray table measurements of the static distributions to compute three 2-D distribution at three heights using a filtered back-projection algorithm. These distributions are interpolated to generate a 3-D matrix of repartition at various heights. This 3-D matrix is used as nozzle distribution description in a dynamic distribution model where the dynamic distribution is computed as a summation of the static distribution at successive positions. The model kernel was found suitable to predict the repartition under a moving boom. [less ▲]

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See detailApplication of image analysis to the identification and rating of road surface distress
Rasse, Catherine; Leemans, Vincent ULg; Destain, Marie-France ULg et al

in Correia; Branco (Eds.) Bearing Capacity of Roads, Railways and Airfields (2002)

Numerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient ... [more ▼]

Numerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient lighting, presence of humidity and because of the poor contrast of the cracks with regard to road texture. The paper presents algorithms suited to detect random cracks edges in a noisy environment in three stages. The pre-treatment consisted mainly in applying a background correction to eliminate the heterogeneity due to humidity, shade, ... In the treatment, a threshold value was applied to segment the 'object' from the rest of the image. As these objects may be cracks, part cracks, or some noise erroneously segmented as defect, a post-treatment was applied to appreciate more accurately if a pixel belonged to an object or to the background. It aimed also to assembly parts of the cracks in continuous structure. When compared to visual detection, efficient detection of cracks is obtained. Further work needs to be done to get an automatic detection of the cracks whatever the road texture. [less ▲]

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See detailSpray controller for horizontal boom movements compensation
El Bahir, Loussain; Lebeau, Frédéric ULg; Destain, Marie-France ULg et al

in Proceedings of AgEng2002 (2002)

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension ... [more ▼]

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods show performance and price limitations. The purpose of this paper is to propose a spray controller aiming to compensate the effect of the horizontal boom movements on the spray distribution besides the effect of tractor speed variations. The controller is based on three main parts: a control law describing the relationship between nozzle speed, nozzle flow and spray coverage; a real time measurement of the boom horizontal speed variations using micro-machined capacitive accelerometers and Pulse Width Modulation (PWM) no zzle flow actuators. A prototype was developed using a processor board controller (dSpace) and tested on a laboratory test bench. The nigrosine solution spray coverage was measured using image analysis for field representative multi-sine nozzle speed variations. The spray coverage uniformity using the spray controller showed about 51% compensation of the spray coverage variations observed without controller. [less ▲]

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See detailMapping within-field soil variability for precision agriculture using electromagnetic induction
Hanquet, Bernard; Frankinet, Marc; Parez, Vincent et al

in Proceedings of AgEng (2002)

Among the crops production factors, the soil is obviously one of the most important. Therefore, within the context of Precision Agriculture, the spatial variability knowledge of its physical and chemical ... [more ▼]

Among the crops production factors, the soil is obviously one of the most important. Therefore, within the context of Precision Agriculture, the spatial variability knowledge of its physical and chemical properties is essential as a decision support information for cultural operations modulation. The purpose of this study is to assess the capability of electromagnetic induction sensing of apparent electrical conductivity (ECa) for the characterisation of withinfield variability of soil physical and/or chemical properties in the particular soil conditions encountered in our experimental area, namely non-saline deep silty soils. ECa maps were produced on a 7ha field in April 2001, September 2001 and April 2002. Concurrently, an intensive soil survey (112 points) was carried out in February 2001 in order to determine a series of physical, textural and chemical soil parameters. ECa accurately described clay content, and exchangeable K and Ca cations concentrations. [less ▲]

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See detailDevelopment of a multibody model of a sprayer
Ooms, David ULg; Lebeau, Frédéric ULg; Maton, Nicolas et al

in Proceedings of AgEng (2002)

A multibody model of a sprayer boom including the suspension was developed by using ADAMS 11.0 (Mechanical Dynamics). The model was designed with the aim to describe the dynamic behaviour of different ... [more ▼]

A multibody model of a sprayer boom including the suspension was developed by using ADAMS 11.0 (Mechanical Dynamics). The model was designed with the aim to describe the dynamic behaviour of different types of booms and suspensions (double trapezium, trapezium, pendulum, …). This was obtained by creating a general model in which geometrical (dimensions) and mechanical parameters (mass and inertia, friction coefficients, stiffness and damping coefficients of the hinges, …) of the system were easily modified. A graphical interface especially designed authorised this easy modification. The validation of the model was obtained by measuring in real conditions the frame movements as solicitations and the boom movements as responses. The method was applied on a trailed sprayer equipped with a boom of 24 m and a trapezoidal suspension. Good accordance was found between measured and simulated vertical displacements. The model may decrease the development costs of suspension and boom designs. [less ▲]

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See detailEvaluation of tactile sensors in apple firmness measurement
Petit, Catherine; Leemans, Vincent ULg; Kleynen, Olivier et al

in Proceedings of the Conference 'Physical Methods in Agriculture, Appoach to precision and quality' (2001)

The objective of the work consists to develop a non-destructive fruit firmness measurement. The tactile sensor technology was chosen. The force measurement acting between the fruit-sensor as well as the ... [more ▼]

The objective of the work consists to develop a non-destructive fruit firmness measurement. The tactile sensor technology was chosen. The force measurement acting between the fruit-sensor as well as the contact area are coupled with other meaqsurements, like the color of the fruit. The results of the measurements are compared with the firmness reference values (Magness-Taylor test) and also with the acoustic impulse response technique. Several parameters correlated with firmness are proposed. [less ▲]

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See detailDéveloppement de méthodes pour apprécier 'en ligne' la qualité externe de pommes par vision artificielle
Leemans, Vincent ULg; Destain, Marie-France ULg; Magein, Hugo ULg

Book published by Ministère des Classes moyennes et de l'Agriculture - DG6 -Service Recherche subventionnée (2001)

L'ouvrage présente les résultats des recherches effectuées pour mettre au point un système de tri automatisé pour pommes, en fonction des critères de qualité externe, la couleur, la forme et la présence ... [more ▼]

L'ouvrage présente les résultats des recherches effectuées pour mettre au point un système de tri automatisé pour pommes, en fonction des critères de qualité externe, la couleur, la forme et la présence de défauts. [less ▲]

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See detailSensor Data Fusion for the Measurement of Horizontal Sprayer Boom Displacement
Lebeau, Frédéric ULg; Destain, Marie-France ULg

Conference (2000, September 14)

The measurement of horizontal sprayer boom movements is an important parameter for the simulation of repartition generated by a sprayer in the dynamic environment of agricultural fields. The existing ... [more ▼]

The measurement of horizontal sprayer boom movements is an important parameter for the simulation of repartition generated by a sprayer in the dynamic environment of agricultural fields. The existing methods were unsatisfactory for diverse reasons as limited measurement length or insufficient accuracy. Two different sensor data fusion methods were evaluated as input for a model aimed at predicting longitudinal spray deposit. A combination of radar and two accelerometers measurements was found more suited than laser and radar measurements combined in predicting spray repartition. [less ▲]

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